Another way to think of this issue is through the idea of an archetypal photographs. When someone thoughtful says "everything has been photographed!" what they really mean is that virtually every photograph that one might take today will closely resemble an archetypal photograph which has been made many times before.

How closely will your picture resemble the archetype? How overdone is the archetype, anyways?

These questions depend, of course, on your picture and on the archetype. Still, it's generally fair to say that your picture (whatever it might be) does indeed closely resemble some archetype or another, and fairly closely.

So what? Is it OK if you just want to make pleasing instances of this archetype or that? Sure. Why not? When I cook, I don't feel the need to push the boundaries. A good quality example of the "Fettuccine Alfredo" archetype or the "pecan pie" archetype is a glorious thing.

What if you're not happy with that, though?

You can try to inch away from the archetype. Make a photograph that's similar to the archetype, but finds a way to be new. Of, if it can't be new, make it personally interesting to you. Or find some way to make it interesting while still being archetypal.

Taking pictures of people is always good. You can take a completely vanilla portrait, an extremely pure example of an archetype, and it's still interesting to most people because it's a picture of a person, and we like looking at people. We, as people, think people are pretty interesting.

The other thing you can do, which is my baseline position, is step beyond the archetype. Let your pictures by examples of this archetype or that, in the same way you let the pixels be this color or that color. You needn't invent a new shade of grey to say something interesting. You don't need to invent a new word to say something interesting.

Make a body of work.

Edward Weston was a mighty maker of "haiku", but that time is long past. Now we (usually, but not always) have to write novels, if we want to make a personal statement of much weight.